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The Impact of Climate and Land Cover Change on the Cryosphere and Hydrology of the Mackenzie River Basin, Canada.

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Bibliographische Detailangaben
Titel: The Impact of Climate and Land Cover Change on the Cryosphere and Hydrology of the Mackenzie River Basin, Canada.
Autoren: Elshamy, Mohamed E., Pomeroy, John W., Pietroniro, Alain, Wheater, Howard, Abdelhamed, Mohamed
Quelle: Water Resources Research; Dec2025, Vol. 61 Issue 12, p1-28, 28p
Schlagwörter: CLIMATE change, HYDROLOGY, WATERSHEDS, GLACIATION, FROZEN ground, WATER supply, ENVIRONMENTAL history
Geografische Kategorien: ARCTIC regions, CANADA, MACKENZIE River (N.W.T.)
Abstract: Northern basins are projected to continue warming at rates higher than the global average, with the impacts of warming compounded by concomitant deglaciation, permafrost thaw and vegetation shifts. The Mackenzie River Basin drains headwaters in the glaciated Canadian Rockies to the Arctic Ocean and is mostly underlain by permafrost. Scenarios of future change in this basin were simulated using the MESH distributed hydrological‐cryospheric land surface model. MESH was forced with bias‐corrected, downscaled RCM forcings and parameterized with a deep subsurface profile, organic soils, and glaciers. The model, validated against discharge, snowpack, and permafrost observations, was used to simulate 21st century hydrology and permafrost dynamics under the RCP8.5 emissions scenario, incorporating projected land cover change applied at two discrete time steps (2021 and 2065). The findings indicate a rapid acceleration of permafrost thaw. By the 2080s, most of the basin will be devoid of permafrost. By late century, river discharges shift to earlier and higher peaks in response to projected increases in precipitation, temperature and snowmelt, despite increases in evapotranspiration from longer snow‐free seasons. Baseflow discharges increase in winter, due to higher precipitation and increased basin connectivity from permafrost thaw resulting in enhanced groundwater flow. Subsurface moisture storage rises slightly but the liquid water fraction increases dramatically, increasing subsurface runoff and river discharge. Canadian Rockies' deglaciation reduces summer and annual discharge in the Athabasca and Peace headwaters. Downstream and northward of the mountain headwaters the direct impacts of climate change on river discharge dominate those of changing land cover and glaciers. Plain Language Summary: The Mackenzie River Basin, a large northern water system that stretches from the Canadian Rockies to the Arctic Ocean, is undergoing large changes due to rapid climate warming in northern latitudes. This study simulated how climate and land cover changes could impact the basin's water flows and permafrost (frozen ground for at least 2 years) using a land surface model. It is expected that climate change will bring warmer temperatures and higher precipitation over the basin. The model predicts that most permafrost areas will disappear by the 2080s. Permafrost thaw could lead to more groundwater flow and higher winter river levels as more water moves through the ground. Warmer temperatures will cause snow to melt earlier, resulting in higher river flows earlier in the year. Additionally, as glaciers in the Rockies melt, summer river flows will decrease, especially in headwater areas like the Athabasca and Peace Rivers. However, the overall effect of warmer temperatures and increased rainfall will likely be stronger than changes from shrinking glaciers and other land cover changes. These findings highlight the need for planning for and adapting to shifts in northern river systems due to climate change. Key Points: Streamflow is expected to peak higher and earlier for most subbasins of the Mackenzie River Basin in response to climate changeMost of the basin is expected to be permafrost‐free by 2080s under RCP8.5 resulting in higher connectivity and larger subsurface flowsDeglaciation of mountainous headwaters is expected to reduce summer flows with implications for water resources management and navigation [ABSTRACT FROM AUTHOR]
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Datenbank: Biomedical Index
Beschreibung
Abstract:Northern basins are projected to continue warming at rates higher than the global average, with the impacts of warming compounded by concomitant deglaciation, permafrost thaw and vegetation shifts. The Mackenzie River Basin drains headwaters in the glaciated Canadian Rockies to the Arctic Ocean and is mostly underlain by permafrost. Scenarios of future change in this basin were simulated using the MESH distributed hydrological‐cryospheric land surface model. MESH was forced with bias‐corrected, downscaled RCM forcings and parameterized with a deep subsurface profile, organic soils, and glaciers. The model, validated against discharge, snowpack, and permafrost observations, was used to simulate 21st century hydrology and permafrost dynamics under the RCP8.5 emissions scenario, incorporating projected land cover change applied at two discrete time steps (2021 and 2065). The findings indicate a rapid acceleration of permafrost thaw. By the 2080s, most of the basin will be devoid of permafrost. By late century, river discharges shift to earlier and higher peaks in response to projected increases in precipitation, temperature and snowmelt, despite increases in evapotranspiration from longer snow‐free seasons. Baseflow discharges increase in winter, due to higher precipitation and increased basin connectivity from permafrost thaw resulting in enhanced groundwater flow. Subsurface moisture storage rises slightly but the liquid water fraction increases dramatically, increasing subsurface runoff and river discharge. Canadian Rockies' deglaciation reduces summer and annual discharge in the Athabasca and Peace headwaters. Downstream and northward of the mountain headwaters the direct impacts of climate change on river discharge dominate those of changing land cover and glaciers. Plain Language Summary: The Mackenzie River Basin, a large northern water system that stretches from the Canadian Rockies to the Arctic Ocean, is undergoing large changes due to rapid climate warming in northern latitudes. This study simulated how climate and land cover changes could impact the basin's water flows and permafrost (frozen ground for at least 2 years) using a land surface model. It is expected that climate change will bring warmer temperatures and higher precipitation over the basin. The model predicts that most permafrost areas will disappear by the 2080s. Permafrost thaw could lead to more groundwater flow and higher winter river levels as more water moves through the ground. Warmer temperatures will cause snow to melt earlier, resulting in higher river flows earlier in the year. Additionally, as glaciers in the Rockies melt, summer river flows will decrease, especially in headwater areas like the Athabasca and Peace Rivers. However, the overall effect of warmer temperatures and increased rainfall will likely be stronger than changes from shrinking glaciers and other land cover changes. These findings highlight the need for planning for and adapting to shifts in northern river systems due to climate change. Key Points: Streamflow is expected to peak higher and earlier for most subbasins of the Mackenzie River Basin in response to climate changeMost of the basin is expected to be permafrost‐free by 2080s under RCP8.5 resulting in higher connectivity and larger subsurface flowsDeglaciation of mountainous headwaters is expected to reduce summer flows with implications for water resources management and navigation [ABSTRACT FROM AUTHOR]
ISSN:00431397
DOI:10.1029/2024WR039276